1. Technical Field
The present invention relates to a printing apparatus, and more particularly, to an apparatus for printing an image on a card supported on its one side by a platen roller by bringing a thermal head into press-contact with the card via an ink ribbon.
2. Description of the Related Art
Conventionally, apparatuses have been known which print an image on a printing sheet supported on its one side by a platen roller by bringing a thermal head into press-contact with the sheet via an ink ribbon. In the aforementioned apparatuses, when press-contact of the thermal head is released after finishing printing, the ink ribbon sags, and is in contact with the platen roller. When a printing sheet is fed in this state, such a case arises that the sagging ink ribbon winds itself around the platen roller by the effect of static electricity.
Then, to solve this problem, for example, Japanese Patent Application Publication No. 2009-113228 discloses a configuration, in a printing apparatus using an ink ribbon with a plurality of colors arranged panel-sequentially, where the ink ribbon is reeled to resolve the sag of the ink ribbon, and further, subsequent positioning of the next color of the ink ribbon is performed.
Further, in the aforementioned printing apparatus, generally, a peeling plate 60 is provided near the thermal head to peel off the ink ribbon from a printing sheet (card) (see FIG. 10). In addition, it is defined that a point in which an ink ribbon R peels off from a card C is a peeling point, and that a distance from a thermal head 51 to the peeling point is α. In such a printing apparatus, after printing on the card C is finished, the thermal head 51 is not raised immediately, the ink ribbon R is reeled while transporting the card for the distance α, and then, the printing operation is finished (see FIG. 11). According to this configuration, when all-surface printing on the card C is performed, after the card is passed through between the thermal head and platen roller, the thermal head 51 drops onto the platen roller 44. Then, the ink ribbon R is pulled out of a supply spool 54 by force of a drop of the thermal head 51, and as a result, the ink ribbon R sags (see FIG. 12).
However, as described above, since transport of the card and reeling of the ink ribbon is performed from the printing finish position (card rear end) to the position of the peeling point, the sag of the ink ribbon is resolved during this period. Thereafter, the thermal head is raised and the ink ribbon is reeled.
However, when the printing finish position is within α from the card rear end, during the time the ink ribbon R is reeled while transporting the card C for the distance α after printing is finished, the card rear end is passed through between the thermal head 51 and the platen roller 44, and the thermal head 51 drops. Accordingly, when the printing operation is finished immediately after the thermal head 51 drops (the state in FIG. 14), the thermal head 51 is raised while the sag of the ink ribbon R remains. When the platen roller 44 is rotated thereafter, the ink ribbon R winds itself around the platen roller 44, and an error occurs (see FIG. 16).
In view of the aforementioned matter, it is an object of the invention to provide a printing apparatus and printing method for resolving sag of an ink ribbon pulled out by a drop of a thermal head when a printing finish position is in the vicinity of the card rear end, and eliminating winding of the ink ribbon around the platen roller.